This invention relates to a bumper beam arrangement for a vehicle, comprising a bumper beam that has an open profile with a top end and two sides, wherein the beam is mounted on two crash boxes, which protrude into the profile and are mounted to the top end of the profile.
To mount bumper beams in crash boxes is known for example from EP-0763448 A1, DE-19537186 A1, DE-4127381 A1, and U.S. Pat. No. 3,998,485 A1. The crash boxes take up energy in a crash by being plastically deformed axially. The strength of the crash boxes can be designed for high-speed crashes, but crash boxes can alternatively be designed for low speed crashes.
U.S. Pat. No. 3,998,485 A1 shows crash boxes for low speed crashes in the form of tubes with a constant cross section, in which a bumper beam with a U-formed cross section is mounted. When a crash box is axially compressed, the two sides of the bumper beam will be forced into the body of the vehicle and cause damages also in a crash at very low speed. In a light offset crash on one of the crash boxes, this crash box will be axially compressed while the bumper beam will practically not be deformed. Yet, the bumper beam will damage the vehicle body. Conical crash boxes are shown at the rear of the tube formed crash boxes and these conical crash boxes are adapted not to be deformed until the tube formed crash boxes have been compressed.
Bumper beams having hat profile are shown for example in WO-94/0770.
It is an object of the invention to reduce the risk of damage on the body in low velocity crashes and in particular in such offset crashes. To this end, the crash boxes taper off and protrudes into the profile with their narrow ends so that the crash boxes force the sides of the profile to widen the profile and make it flatter when the crash boxes are axially compressed. The invention is defined by the claims.